1. Field of the Invention
This invention relates in general to communicating with a subset of nodes in a wireless network. In particular, the invention relates to a method, apparatus and system for multicast communication with a subset of nodes in a general wireless ad hoc network or in a network of nodes that comply with the ZigBee network standard specification.
2. Discussion of the Background
Conventional communication network protocols may include a method of sending a message to one or more specifically addressed nodes (i.e., unicast communication), and may also include a method of sending a message to all nodes in a network or network segment (i.e., broadcast communication). However, conventional communication network protocols may not include an efficient method of sending messages to a particular subset of nodes using a single address (i.e., multicast communication).
Charles E. Perkins and Elizabeth Royer, “Ad-hoc On-Demand Distance Vector Routing”, Proceedings of the 2nd IEEE Workshop on Mobile Computing Systems and Applications, New Orleans, La., February 1999, pp. 90-100, incorporated by reference herein in its entirety, describes a conventional routing protocol called On-Demand Distance Vector Routing (AODV) that may be used for route discovery between pairs of nodes in general wireless ad hoc networks. Elizabeth Royer and Charles E. Perkins, “Multicast Operation of the Ad-hoc On-Demand Distance Vector Routing Protocol”, Proceedings of MobiCom '99, Seattle, Wash., August 1999, pp. 207-218, incorporated by reference herein in its entirety, describes an extension of AODV called Multicast On-Demand Distance Vector Routing (MAODV) to establish multicast groups in general wireless ad hoc networks.
However, there are some problems and inefficiencies associated with the MAODV multicast approach. MAODV uses only a simple hop count as a measure of routing cost, which may be an unreliable metric. Further, MAODV is presented in the literature as merely a method to establish multicast groups in general ad hoc networks, but the description of MAODV does not take into consideration any specific network or application scenarios, and does not solve the problem of identifying a particular method of data delivery to nodes in the established multicast group. In addition, MAODV relies on existing unicast RREQ and RREP command frames to perform multicast join functions, MAODV uses the MACT command frame during both selected route activation and while a node is leaving a multicast group, and MAODV may make excessive use of inefficient network level broadcast messages for message propagation.